Superconducting quantum circuitry is a key modern technology presently under development worldwide, it contributes variously to fields such as quantum computing, quantum simulation, microwave quantum optics and the study of ’artificial atoms’. It is a rapidly developing field worldwide with much recent progress. An important and topical area based on superconducting quantum circuits is that of quantum limited sensing and quantum limited amplification. The development of this capability is thought likely necessary to underpin many aspects of the new superconducting quantum technologies.
At Royal Holloway significant progress has been made on exploiting the non-linearity of the Josephson junction to produce extremely sensitive detectors based on complex quantum electrodynamical bifurcations in resonant superconducting cavities. Such measurement techniques can beat the well-known resonant quality-factor gain of high-Q superconducting resonators and are potentially so-called quantum non-demolition measurements, but they achieve this at the expense of dynamic range and bandwidth. A newer concept, the so-called travelling-wave amplifier has also recently been demonstrated elsewhere and, related, the opportunity to beat the so-called standard quantum limit to sensitivity exists through the exploitation of squeezed quantum states. Such advances may hold the key to future flexible, robust quantum technologies of ultimate sensitivity.
The project proposed here will build on the current state-of-the-art to design, fabricate and study both bifurcation and travelling wave amplifiers based on superconducting resonant cavities and non-resonant structures. The aims are to create devices capable of detecting single microwave photons, provide new readout mechanisms for superconducting qubits and provide a means to study and understand fundamental aspects of quantum limited amplification.
The project is predominantly experimental and the student will spend much of their their time designing and nano-fabricating quantum circuits and making measurements at low temperatures. The student will develop skills in quantum theory, dilution refrigerator and other cryogenic technology, microwave technology, device design and other experimental, analytical and modelling techniques. The emphasis will be on obtaining quantitative data about the behaviour of non-linear microwave superconducting quantum circuits at milliKelvin temperatures at the quantum limit. The overarching aim is to understand and exploit the quantum processes of measurement, control and photonic amplification at the quantum limits of sensitivity and beyond. The student will be based primarily at Royal Holloway, University of London with a co-supervisor at The National Physical Laboratory.
This demanding but rewarding project will be undertaken within the "UK Centre for Superconducting and Hybrid Quantum Systems" (UK-CSQS), a joint venture between Royal Holloway, University of London, the University of Lancaster and the National Physical Laboratory. The overall research focus of the centre is the development of quantum device technology through the application of fundamental phenomena based on superconductivity, such as the Josephson effects, coherent quantum phase slip (the dual of the Josephson effect), flux and charge quantisation, quantum coherent behaviour, the principle of superposition, non-linear and non-dissipative phenomena, quantum entanglement and the interaction of devices with the quantised electromagnetic field, both as a probe and as an environment. We provide shared access to nano-fabrication facilities, specialist cryogenic facilities, an advanced understanding of condensed matter quantum technologies and we share our expertise. We also seek advances in the related fields of materials discovery and exploitation, low temperature technology, microwave technology and advanced nano-fabrication. Potential applications lie in the fields of quantum metrology (seeking to re-define the Ampere and to close the ‘metrological triangle’), the construction of quantum computing devices and quantum simulators, the exploitation of artificial atoms, microwave quantum optics, quantum meta-materials, quantum limited amplification and novel sensors operating beyond the standard quantum limit. The integration of these devices with other quantum systems such as nano electromechanical systems (NEMS), embedded ions, magnetic materials, normal metals, semiconductor and low-dimensional materials and other forms of quantum system is the basis of Hybrid Devices. The three groups each have outstanding global reputations for their research.
Applications may be submitted at any time. Several projects are available within the UK-CSQS, applicants should submit only one application and specify their interests to be considered for all available relevant projects.
This research project has funding attached. Funding for this project is available to citizens of a number of European countries (including the UK). In most cases this will include all EU nationals. However full funding may not be available to all applicants and you should read the full department and project details for further information.
Non-European Students: In most cases if you have the correct qualifications and access to your own funding, either from your home country or your own finances, your application to work with this supervisor will be considered.